map-reduce-simple.clj

 (defn map-reduce [map-fn reduce-fn n xs]
  (let [bspec {:type :mem :merge reduce-fn}
        bs (repeatedly n #(bucket/new bspec))
        work (fn [b x]
              (doseq [[k v] (map-fn x)]
                (bucket/merge b k v)))
        ;; each worker gets own bucket 
        ;; so no contention
        workers (map #(partial work %) bs)]
      ;; workers process xs in par, blocking
      (do-work workers xs)
      ;; merge all bucket users
      (reduce bucket/merge-all bs)))